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/**
* @file sunLightSSAOF.glsl
* $LicenseInfo:firstyear=2007&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2007, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#extension GL_ARB_texture_rectangle : enable
#ifdef DEFINE_GL_FRAGCOLOR
out vec4 frag_color;
#else
#define frag_color gl_FragColor
#endif
//class 1 -- no shadow, SSAO only
uniform sampler2DRect depthMap;
uniform sampler2DRect normalMap;
uniform sampler2D noiseMap;
// Inputs
uniform float ssao_radius;
uniform float ssao_max_radius;
uniform float ssao_factor;
uniform float ssao_factor_inv;
VARYING vec2 vary_fragcoord;
uniform mat4 inv_proj;
uniform vec2 screen_res;
#ifdef SINGLE_FP_ONLY
vec2 encode_normal(vec3 n)
{
vec2 sn;
sn.xy = (n.xy * vec2(0.5f,0.5f)) + vec2(0.5f,0.5f);
return sn;
}
vec3 decode_normal (vec2 enc)
{
vec3 n;
n.xy = (enc.xy * vec2(2.0f,2.0f)) - vec2(1.0f,1.0f);
n.z = sqrt(1.0f - dot(n.xy,n.xy));
return n;
}
#else
vec2 encode_normal(vec3 n)
{
float f = sqrt(8 * n.z + 8);
return n.xy / f + 0.5;
}
vec3 decode_normal (vec2 enc)
{
vec2 fenc = enc*4-2;
float f = dot(fenc,fenc);
float g = sqrt(1-f/4);
vec3 n;
n.xy = fenc*g;
n.z = 1-f/2;
return n;
}
#endif
vec4 getPosition(vec2 pos_screen)
{
float depth = texture2DRect(depthMap, pos_screen.xy).r;
vec2 sc = pos_screen.xy*2.0;
sc /= screen_res;
sc -= vec2(1.0,1.0);
vec4 ndc = vec4(sc.x, sc.y, 2.0*depth-1.0, 1.0);
vec4 pos = inv_proj * ndc;
pos /= pos.w;
pos.w = 1.0;
return pos;
}
//calculate decreases in ambient lighting when crowded out (SSAO)
float calcAmbientOcclusion(vec4 pos, vec3 norm)
{
float ret = 1.0;
vec2 kern[8];
// exponentially (^2) distant occlusion samples spread around origin
kern[0] = vec2(-1.0, 0.0) * 0.125*0.125;
kern[1] = vec2(1.0, 0.0) * 0.250*0.250;
kern[2] = vec2(0.0, 1.0) * 0.375*0.375;
kern[3] = vec2(0.0, -1.0) * 0.500*0.500;
kern[4] = vec2(0.7071, 0.7071) * 0.625*0.625;
kern[5] = vec2(-0.7071, -0.7071) * 0.750*0.750;
kern[6] = vec2(-0.7071, 0.7071) * 0.875*0.875;
kern[7] = vec2(0.7071, -0.7071) * 1.000*1.000;
vec2 pos_screen = vary_fragcoord.xy;
vec3 pos_world = pos.xyz;
vec2 noise_reflect = texture2D(noiseMap, vary_fragcoord.xy/128.0).xy;
float angle_hidden = 0.0;
int points = 0;
float scale = min(ssao_radius / -pos_world.z, ssao_max_radius);
// it was found that keeping # of samples a constant was the fastest, probably due to compiler optimizations unrolling?)
for (int i = 0; i < 8; i++)
{
vec2 samppos_screen = pos_screen + scale * reflect(kern[i], noise_reflect);
vec3 samppos_world = getPosition(samppos_screen).xyz;
vec3 diff = pos_world - samppos_world;
float dist2 = dot(diff, diff);
// assume each sample corresponds to an occluding sphere with constant radius, constant x-sectional area
// --> solid angle shrinking by the square of distance
//radius is somewhat arbitrary, can approx with just some constant k * 1 / dist^2
//(k should vary inversely with # of samples, but this is taken care of later)
angle_hidden = angle_hidden + float(dot((samppos_world - 0.05*norm - pos_world), norm) > 0.0) * min(1.0/dist2, ssao_factor_inv);
// 'blocked' samples (significantly closer to camera relative to pos_world) are "no data", not "no occlusion"
points = points + int(diff.z > -1.0);
}
angle_hidden = min(ssao_factor*angle_hidden/float(points), 1.0);
ret = (1.0 - (float(points != 0) * angle_hidden));
return min(ret, 1.0);
}
void main()
{
vec2 pos_screen = vary_fragcoord.xy;
//try doing an unproject here
vec4 pos = getPosition(pos_screen);
vec3 norm = texture2DRect(normalMap, pos_screen).xyz;
norm = decode_normal(norm.xy);
frag_color[0] = 1.0;
frag_color[1] = calcAmbientOcclusion(pos, norm);
frag_color[2] = 1.0;
frag_color[3] = 1.0;
}
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